pascal (Pa), unit ofpressure andstress in the metre-kilogram-second system (theInternational System of Units [SI]). It was named in honour of the French mathematician-physicistBlaise Pascal (1623–62). A pascal is a pressure of onenewton persquaremetre, or, in SI base units, onekilogram per metre per second squared. This unit is inconveniently small for many purposes, and thekilopascal (kPa) of 1,000 newtons per square metre is more commonly used. For example, standardatmospheric pressure (or 1 atm) is defined as 101.325 kPa. Themillibar, a unit of air pressure often used inmeteorology, is equal to 100 Pa. (For comparison, onepound per squareinch equals 6.895 kPa.)